What type of mortgage would a developer typically use for his development?

In the context of real estate development, a developer typically utilizes a construction loan to finance the building of new properties. This type of loan is specifically designed to cover the costs associated with the construction phase of a project. Construction loans provide short-term financing that allows developers to pay for materials, labor, permits, and other related expenses until the project is completed. Once the construction is finished, the loan can often be converted into a permanent mortgage, allowing for a more traditional financing structure afterward.

While a blanket mortgage could be applicable in some circumstances, as it covers multiple properties under one loan, it is not the most common choice specifically geared towards the construction phase. Conventional and fixed-rate mortgages are more appropriate for existing properties rather than new developments. Therefore, a construction loan is the most fitting option for developers seeking to build new constructions, making it the correct answer.