Complete analogous pair - Chromite : Chromium : : Ilmenite : ?

D. TITANIUM

In the following question, a matrix of certain characters is given. These characters follow a certain trend, row-wise or column-wise. Find out this trend and choose the missing character accordingly.
7 4 5
8 7 6
3 3 ?
29 19 31

C. 5

Complete analogous pair - Scout : Army : : Clerk : ?

A. OFFICE

Complete analogous pair - Quail : Partridges : : Yark : ?

C. OXEN

Complete analogous pair - Heart : Pericardium : : Brain : ?

D. CRANIUM