In this task, you're given a question, a context passage, and four options which are terms from the passage. After reading a passage, you will get a brief understanding of the terms. Your job is to determine by searching and reading further information of which term you can answer the question. Indicate your choice as 'a', 'b', 'c', or 'd'. If you think more than one option is plausible, choose the more probable option to help you answer the question.
Q: Question: What was the lithography previous to 45 nm? Passage:The Intel Core microarchitecture (previously known as the Next-Generation Micro-Architecture) is a multi-core processor microarchitecture unveiled by Intel in Q1 2006. It is based on the Yonah processor design and can be considered an iteration of the P6 microarchitecture introduced in 1995 with Pentium Pro. High power consumption and heat intensity, the resulting inability to effectively increase clock speed, and other shortcomings such as an inefficient pipeline were the primary reasons why Intel abandoned the NetBurst microarchitecture and switched to a completely different architectural design, delivering high efficiency through a small pipeline rather than high clock speeds. The Core microarchitecture initially did not reached the clock speeds of the NetBurst microarchitecture, even after moving to 45 nm lithography. However after many generations of successor microarchitectures which used Core as their basis (such as Nehalem, Sandy Bridge and more), Intel managed to eventually surpass the clock speeds of Netburst with the Devil's Canyon (Improved version of Haswell) microarchitecture reaching a base frequency of 4 GHz and a maximum tested frequency of 4.4 GHz using 22 nm lithography. 
 Links: a. Central processing unit b. 45 nanometer c. Pentium Pro d. Central processing unit
A: 
b