As a result of howard hughes sr.’s contributions to the petroleum industry — a) offshore drilling was safer b) oil drilling was possible through hard rock c) transportation of oil products was more efficient d) oil refineries were located exclusively in texas

The answer is B, oil drilling was possible through hard rock.

Explanation:

There are times when new advancements are proposed as being better methods for penetrating for oil and flammable gas. In any case, to see how these are better (or more probable not) than existing advances, you need to know how the business regularly bores through the shake. There are two fundamental methods for doing as such, contingent upon how hard the stone is. The first is the one that made the Hughes family exceptionally rich. The other, fairly slower, was created the last time that we had a vitality emergency, and utilization fake jewels, in the principle, to gouge into and rub off thin layers of shake.

explanation:

hitler's  "rise" can be considered to have ended in march 1933, after the reichstag adopted the enabling act of 1933 in that month. president paul von hindenburg had already appointedhitler  as chancellor on 30 january 1933 after a series of parliamentary elections and associated backroom intrigues.