= Solution
\b[A: currently inactive; B: active <left-lateral strike-slip faulting>; C: active <normal faulting>.]
A lies on the continuation of the offset outside the two ridge tips: it is the <fracture zone>, whose two sides are carried in the same overall plate direction. A bathymetric step can remain because the two sides have different ages and thermal histories, without continuing plate-boundary <strike-slip faulting>.
B is the black segment connecting the two white <spreading ridges>. Construct the <plate motion> from divergence away from those ridge axes. Between their tips, the upper side of B belongs to the plate west of the right-hand ridge and moves approximately west-northwest; the lower side belongs to the plate east of the left-hand ridge and moves approximately east-southeast. Looking across B from either side, the opposite side moves to the observer's left. B is therefore a \b[<left-lateral strike-slip faulting> on a <transform fault>]. The offset preserved outside the active segment must not be read as the sense of present slip.
\b[The grey arrows in the source image are pointers to <detachment faults>, not plate-motion vectors.] The original publication identifies white lines as <spreading ridges>, black lines as <transform faults>, and arrows as pointers to detachments. Its Figure 1b is the unlettered source of the exam's Figure 3.<How transform fault shear influences where detachment faults form near mid-ocean ridges by Jana C. Schierjott and others>[2023, Figure 1 caption]{ref}
C lies on the white <spreading ridge> extending down from the left-hand ridge-transform intersection. Relative motion there is extensional, so its tectonic <faults> have \b[normal slip]. <Dike> intrusion also accommodates extension at a <spreading ridge>; “normal slip” is the appropriate category among the four offered, not a claim that all spreading is achieved by a single <normal fault>.
\Image[/past-exam-of-the-plate-tectonics-course-of-the-university-of-oxford/2024-ridge-transform.png]
{title=Why the active transform in the supplied geometry is left lateral}
{description=Original idealized plan-view construction using the supplied ridge arrangement and relative motion directions. It illustrates the kinematic test, rather than reproducing the exam bathymetry.}
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