Which optional subjects should be chosen for preparation of both the IAS and IFS (forest services) at the same time

Which optional subjects should be chosen for preparation of both the IAS and IFS (forest services) at the same time?

See the list of IFoS(IFS) Optional Subjects

(i) Agriculture

(ii) Agricultural Engineering

(iii) Animal Husbandry & Veterinary Science

(iv) Botany

(v) Chemistry

(vi) Chemical Engineering

(vii) Civil Engineering

(viii) Forestry

(ix) Geology

(x) Mathematics

(xi) Mechanical Engineering

(xii) Physics

(xiii) Statistics

(xiv) Zoology

Provided that the candidates will not be allowed to offer the following combination of subjects :

(a) Agriculture and Agricultural Engg.

(b) Agriculture and Animal Husbandry & Veterinary Science.

(c) Agriculture and Forestry.

(d) Chemistry and Chemical Engg.

(e) Mathematics and Statistics.

(f) Of the Engineering subjects viz. Agricultural Engineering, Chemical Engineering, Civil Engineering and Mechanical Engineering—not more than one subject;

See the list of IAS Optional Subjects

Which optional subjects should be chosen for preparation of both the IAS and IFS (forest services) at the same time