the religion iyasus studied —christianity—spread to ethiopia because of

nomadic herding

slavery

trade routes

travel

The religion of Christianity, studied by Iyasus, spread to Ethiopia because of travel.

Explanation:

During the reign of King Ezana, two travellers named Frumentius and Aedissius from Syria came to Ethiopia and began preaching the teachings of Christianity. They somehow managed to convert the king to Christianity and influenced him to declare Christianity as the official religion of the kingdom.Another account of the spread of Christianity to Ethiopia claims that The treasurer eunuch of Ethiopia disseminated Christianity in Ethiopia after returning from his pilgrimage to Jerusalem, way before Frumentius and Aedissius had come to Ethiopia.

Answer is: the amount of heat required to heat the gold is 14336 J.
m(Au) = 3,2 kg · 1000 g/kg = 3200 g.
ΔT = 64°C - 29°C = 35°C.
C = 0,128 J/g·°C.
Q = m(Au) · ΔT · C.
Q = 3200 g · 35°C · 0,128 J/g·°C.
Q = 14336 J = 14,336 kJ.