Without a specified rate of temperature change with altitude, it is impossible to calculate at which altitude the probe's instruments will fail at 601 K.
The question revolves around determining at what altitude the space probe's instruments will fail when entering a gaseous planet's atmosphere where the temperature increases linearly with altitude. Despite the additional context regarding space probes resisting high temperatures and details on Galileo's mission to Jupiter, those specifics aren't directly useful for answering the question with the given options A to E.
The provided temperature data of Venus' atmosphere (Figure 10.12), which shows temperatures at various altitudes, cannot be directly applied here either since the question outlines a linear increase in temperature, no specific temperatures at known altitudes, or a defined rate of temperature change per kilometer of altitude. Consequently, there isn't enough information to determine at which altitude the instruments will fail at 601 K.