Question

marine biologist dr. keira sullivan has documented an unusual protein variation in deep - sea coral that influences calcification rates. this discovery could help explain the resilience of certain coral species in acidifying ____ additional research is necessary to determine its wider ecological significance.
15 mark for review
which choice completes the text so that it conforms to the conventions of standard english?
a oceans; though
b oceans, though,
c oceans though
d oceans, though

Explanation:

To solve this, we analyze the punctuation and conjunction usage. The first part is a complete sentence ("This discovery... acidifying oceans") and the second part ("additional research... significance") is a dependent clause introduced by "though" (a subordinating conjunction). We need a comma to separate the main clause from the subordinate clause introduced by "though". Option A uses a semicolon, which is incorrect as "though" isn't a coordinating conjunction. Option B has an extra comma after "though", which is wrong. Option C has no comma, making it a run - on. Option D uses a comma before "though" to properly introduce the subordinate clause.

Answer:

D. oceans, though